People who are early to bed and early to rise may have their ancient ancestors to thank for the habit – or at least the Neanderthals with whom their forebears procreated, scientists say.
DNA inherited from our thick-browed cousins may contribute to the tendency of some people to be larks, researchers found, making them more comfortable at getting up and going to bed earlier than others.
While most genes that modern humans gained through ancient interbreeding have been weeded out by evolution, a small fraction remain, most probably because they helped early modern humans adapt to the new environment when they left Africa for Eurasia.
Prof Mark Maslin, of University College London, who was not involved in the study, said: “Now we have genetic evidence that some of us really are morning people.
“When humans evolved in tropical Africa, the day lengths were on average 12 hours long. Now hunter gatherers spend only 30% of their awake time collecting food, so 12 hours is loads of time. But the further north you go, the shorter and shorter the days get in winter when food is particularly scarce, so it makes sense for Neanderthals and humans to start collecting food as soon as there is any light to work by.”
